Generally, tire wear test is carried out outdoors by running an actual vehicle mounted with the test tire on a test course or public road. Such wear test in a manner of running test using an actual vehicle not only costs considerably but also involves a problem that, because road conditions change due to the influence of weather, a plurality of test tires are hardly evaluated under the identical conditions.
Therefore, conventionally, there is known a method of tire wear test carried out indoors by simulating running test with an actual vehicle. In such a wear test method, using a testing machine disclosed in, for example, Patent Documents 1 and 2, running modes at running test with the actual vehicle are reproduced indoors by giving conditions of vertical force, camber angle or the like to a test tire rolling on a simulation road surface. However, to carry out the tire wear test precisely, in addition that the running modes have to be reproduced precisely, there arises a problem that handling of various data necessary for the test becomes complicated.
Patent Document 3 below discloses the following method. That is, data of acceleration and speed measured by a running test with an actual vehicle on a test course, and data of three forces on tire axle and camber angle measured during a running test with the actual test vehicle, are converted into load data being associated with each other using a predetermined equation; and running modes are set up based on the load data. However, in such a test method, a test vehicle to be evaluated has to be prepared. The test may be difficult to carry out and/or may cost considerably. Therefore, the test method is not practical.
Non Patent Document 1 below describes a method in which a test course is simulated in a manner of PID (Proportional Integral Derivative) control of a vehicle model, and based on the calculated time-series data with respect to vertical forces and camber angles, running modes are set up. However, in the above test method, running modes during the running test with an actual vehicle are reproduced in time series. Transition of three forces on tire axle and camber angle changing in accordance with the running conditions has to be calculated. And further, running modes have to be set up so that the three forces on tire axle and camber angle are repeated in accordance with the circulation on the test course. As a result, amount of calculation becomes enormously large and the handling of data becomes complicated. Therefore, there arises a problem that a large human power and time are required for setting running modes. In this test method, the severity (running severity level) increased in order to carry out acceleration test (acceleration ratio: four times) to reduce the running time. However, the test results are poor in reproducibility (consistency with test results obtained during running test with an actual vehicle) of the amount of Toe&Heel wear or the like. Therefore, evaluation accuracy is not satisfactorily ensured.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 11-173952
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2005-114605
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2004-522953
Non-Patent Document 1: Deepak Parekh and other three persons, Laboratory Tire Wear Simulation Process Using ADAMS Vehicle Model; Society of Automotive Engineers Paper, No. 961001, (USA), 1996